1. Field of the Invention
The present invention relates to an ink jet recording apparatus and a recovery processing device for said apparatus, and more particularly to an ink jet recording apparatus and a recovery processing device for said apparatus with which the normal ink discharge conditions of an ink jet head are maintained, or having a recovery system for effecting the recovery.
2. Related Background Art
FIG. 5 is a perspective view showing the schematic constitution of the essence of an ink jet recording apparatus pertaining to the background art.
In FIG. 5, C is an ink jet cartridge, comprised of an ink tank portion located upward in the figure, and a recording head located downward, and further provided with a connector for accepting the signals for driving the recording head. The recording head according to this example has a plurality of discharge ports on the bottom face side in the figure, with elements for generating the energy useful to discharge the ink arranged in the liquid channel portions commucating to the discharge ports. Also, each liquid channel communicates to a common liquid chamber in which the ink supplied from the ink tank portion is received. Note that the above elements may be preferably electricity-heat conversion elements for generating the heat energy which serves as the energy for use in discharging the ink, because of the capability of higher integration of discharge ports or liquid channels.
2 is a carriage, which can mount four cartridges C (C1, C2, C3, C4; corresponding to inks of different colors, for example, yellow, magenta, cyan and black) by positioning, and has a connector holder for transmitting the signals for driving the recording head to enable the electrical connection to the recording head.
11 is a scanning rail, extending along the main scan direction of the carriage 2, for supporting the carriage 2 for free sliding movement, and 52 is a drive belt for transmitting the driving force to reciprocate the carriage 2. Also, a conveying roller pair consisting of conveying rollers 15, 16 and a conveying roller pair consisting of conveying rollers 17, 18 are placed before and after the recording position with the recording head to convey the recording medium therebetween. P is the recording medium such as sheet, which is pressed on a platen (not shown) for regulating the record plane of the recording medium P flat. A recording head portion of the ink jet cartridge C mounted on the carriage 2 is protruded downward in the figure from the carriage 2 to be located between recording medium conveying rollers 16, 18, with the discharge port formation face of the recording head portion opposed to and parallel to the recording medium P pressed on a guide plane of the platen (not shown).
In the ink jet recording apparatus of this example, a recovery system unit 200 as recovery means is disposed on the home position side which resides to the left of FIG. 5. In the recovery system unit 200, 300 is a cap unit provided corresponding to a plurality of ink jet cartridges C having recording heads, this cap unit being movable up and down. And when the carriage 2 is located at a home position, it engages and caps the recording head portion, preventing the ink within the discharge ports of the recording head from evaporating, thickening, and fixing to cause a discharge failure.
Also, in the recovery system unit, 500 is a pump unit in communication with the cap unit 300, which is used to produce a negative pressure required for a suction recovery processing which is effected by joining together the cap unit 300 and the recording head in case where any discharge failure accidentally occurs in the recording head. Further, in the recovery system unit, 401 is a blade as a wiping member formed of an elastic material such as rubber, and 402 is a blade holder for holding the blade 401. In this example, with a blade lifting mechanism (not shown) to be driven by the movement of the carriage 2, the blade 401 supported by the blade holder 402 can be set at either of two positions, i.e., a projected (upward) position (wiping position) to wipe the ink adhering to the discharge port formation face of the recording head and a retracted (downward) position (standby position) not to interfere with the discharge port formation face of the recording head.
The pump unit will be described below. This pump unit has a pump for the recovery disposed to such the ink through the discharge ports by utilizing a negative pressure produced by the pump, for the purposes of maintaining the normal ink discharge conditions of the ink jet head or recovering the ink jet head into the normal ink discharge conditions in cases where the clogging occurs in the discharge port. A constitutional example of this pump involves the use of what is called a tube pump which produces negative pressure by changing the volume of a flexible tube (e.g., Japanese Laid-Open Patent Application No. 1-122880).
FIGS. 6A and 6B are views showing the schematic constitution of the tube pump.
First, an opening portion of the cap 30 is brought into contact with the ink jet head 1 to effect the capping on the discharge port formation face 1A. Another opening portion is provided on the back face side of the cap 30, with a tube 3 that is a component of the tube pump connected thereto. A pressure roller 5 is provided for pressing the tube 3, with a shaft portion 5A rotatably supported by a guide roller 4. A shaft portion 4A of the guide roller 4 is attached rotatably to a pump base 6. Also, the pump base 6 is formed with a circular groove 6A which is coaxial with the shaft of the guide roller 4.
In the above constitution, if the guide roller 4 is rotated in a direction of the arrow a by driving means, not shown, the pressure roller 5 on the guide roller 4 makes contact with and presses the tube 3 at a portion of X in FIG. 6A, compressing the tube 3 until the space inside the tube at the pressed portion becomes null. If the guide roller 4 is further rotated in the direction of the arrow a from this state, the pressure roller 5 is caused to rotate in a direction of the arrow b while compressing the tube 3. And it is temporarily stopped at a portion of Y in FIG. 6B. At this time, a negative pressure occurs on the discharge port formation face 1A of the head 1 by volume changes within the tube compressed by the pressure roller 5 which has been moved from the position X to Y, thereby effecting the suction operation through the discharge ports. Also, a waste ink processing member 7 for reserving the ink drawn through the discharge ports owing to suction is disposed downstream of the tube 3.
The recovery operation will be described below in detail using FIGS. 7 and 8.
When the clogging occurs in the discharge ports 1A of the ink jet head 1, the suction recovery operation is performed at the home position.
At the home position, the opening portion of the cap unit 300 is placed into contact with the ink jet head 1 to effect the capping on the discharge port formation face 1A. On the back face side of the cap 300 is provided another opening portion, to which a tube 503 that is a component of the tube pump is connected.
The tube 503 has flexibility at least on the pressed portion, with the pressure roller 505 for pressing that portion attached rotatably around a shaft portion 505A thereof to a roller bearing 508. The roller bearing 508 is held by a columnar shaft 508A, which is accommodated within a hole 504B provided on a guide roller 504 with a compression spring 510 attached around the circumference of the shaft. Also, the roller bearing 508 is secured by an E-type retaining ring. And the pressure roller 505 is biased by the compression spring 510 in a direction of pressing the tube 503. Also, the positioning of the roller bearing 508 is made by a locator pin 508B provided on the roller bearing 508 being guided by a guide groove 504C provided on the guide roller, and the shaft 508A being guided by the guide hole 504B of the guide roller 504.
The shaft portion 504A of the guide roller 504 is rotatably attached to a pump base 506 via a bearing 511. An E-type retaining ring 512 is disposed to prevent the bearing 511 from coming off. Also, a circular groove 506A coaxial with the shaft of the guide roller 504 is formed in the pump base 506. The pump base 506 is attached to a base 513 of the apparatus main body on the opening side of the circular groove 506A. This is aimed to provide the pump base 506 with the function of a cover to cover a pump operation portion with the pump base 506 in the attached state of the pump base 506, thereby preventing the operator from touching the pump operation portion carelessly and causing a malfunction, and preventing the foreign matter from entering the pump operation portion.
The tube 503 is secured by being squeezed within a tube securing groove 506B provided on the pump base 506.
In this way, if the guide roller 504 is rotated in a direction of the arrow a in the pump unit 500, the pressure roller 505 is brought into contact with a roller guide portion 506C formed integrally with the tube securing groove 506B provided on the pump base 506 (at a position Z as indicated by the two-dot chain line in FIG. 7). At this time, the pressure roller 505 is caused to rotate in a direction of the arrow b and move gradually in a direction of the arrow f (toward the center of the roller 504) and upward to a position equivalent to the state where the pressure roller 505 is pressing the tube 503, while being guided by the roller guide portion 506. And if the guide roller 504 is further rotated in the direction of the arrow a, the pressure roller 505 comes into contact with and presses the tube 503 at position X as indicated by the alternate long and short dash line, compressing the tube 503 until the space inside the tube of the pressing portion becomes null. Because when this pressure roller moves from the position Z to the position X, the pressure roller 505 is shifted in the f direction up to a position equivalent to the state where it is already pressing the tube 503 at position Z, and situated at the position Z, it is possible to suppress the abrupt increase of the force acting on the pressure roller 505 when the pressure roller 505 moves to the position X.
If the guide roller 504 is further rotated in the direction of the arrow a from the state with the pressure roller 505 at position X, the pressure roller 505 is caused to rotate in the direction of the arrow b and move while compressing the tube 503. And it is temporarily stopped at position Y as indicated by the dotted line. At this time, a negative pressure produced by volume changes of the tube 503 compressed by the pressure roller 505 during the movement from position X to position Y is exerted on the discharge port formation face 1A of the head 1, effecting the suction operation through the discharge ports.
Note that a waste ink processing member 507 for reserving the ink drawn through the discharge ports by suction is disposed downstream of the tube 503.
After suction, if the guide roller 504 is further rotated in the direction of the arrow a, the pressure roller 505 gradually leaves away from the tube 503 along a roller guide 508C' taking the same configuration as the roller guide 506C. The movement of the pressure roller 505 is reverse to that when the pressure roller 505 makes contact with the tube 503. Hence, the torque variation encountered when the pressure roller 505 is released from the pressed state of the tube 503 can be reduced at this time.
Next, the driving of the pressure roller 505 and the cap unit 300 will be described below with reference to FIGS. 9 to 11. A motor 521 is secured to a housing and has a motor gear 521a at its end portion. An intermediate gear 522 is rotatably supported around its support shaft to the housing, mating with each of a motor gear 521a, a pump gear 504D and a cam gear 523C. The pump gear 504D is formed integrally with the guide roller 504 (see FIG. 8) which axially supports the pressure roller 505 as previously described via a roller bearing. The cam gear 523C, together with a cam 523b formed integrally therewith, is rotatably supported around its support shaft 523a, 523d to the housing. Also, the cap unit 300 is supported to the housing to be movable vertically in the figure by making contact with the cam 523b as shown in FIG. 9, with its vertical position regulated by a normal shaft 302 coming contact with the cam 523b. A pipe 301 of the cap unit 300 is connected to the tube 503 as previously described in connection with the pump. An ink jet head 1 having the discharge port formation face 1A is placed above the cap unit 300.
First, the ink jet head 1 to be subjected to the suction recovery is moved above the cap unit 300 as shown in FIG. 9. If the motor 521 is rotated in a counterclockwise direction as indicated by A in the figure, the pump gear 504D and the cam gear 523C are rotated via the intermediate gear 522 in the same counterclockwise direction as indicated by A. Then, the cap unit 300 in contact with the cam 523b is moved in the upward direction in the figure to cap the discharge port formation face 1A as shown in FIG. 11. At the same time, the pressure roller 505 compresses the tube 503 as shown in FIG. 11 as the roller is rotated, so that a negative pressure is produced in accordance with the process as previously described to such the ink from the discharge port formation face 1A. If the motor A is further rotated, the pressure roller 505 is brought into a state as indicated by the two-dot chain line in FIG. 11 and the suction is stopped. At this time, the cam 523b also resides in a state as indicated by the two-dot chain line to maintain the capping state. If the motor A is further rotated, the cap unit 300 begins to fall, resulting in a cap open state as shown in FIG. 9.
However, in the above example pertaining to the background art, albeit an advantage that the driving of the pump and the driving of the cam for capping can be effected with a single driving source, there was a problem that only one type of the ink suction amount can be set because the respective driving is interlinked.
That is, the motor driving to operate the pump is stopped halfway, the suction amount less than that at the maximum stroke can be obtained, but if the motor is further driven to open the cap, the suction operation is resumed, resulting in the final suction amount being equal to that at the maximum stroke. As a result, the ink may be sucked by the maximum suction amount, depending on the state of the ink jet head, even though the recovery can be effected only with a small suction amount, and the ink is wastefully consumed.
If one suction amount of the pump is set to the minimum value as necessary to eliminate the waste of the ink, the pump must be rotated by many times when the maximum suction amount is required, giving rise to a waste of time as well as causing a durable problem because of the repeated contact and separation between the ink jet head and the cap which is essentially unnecessary.